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  • 1980-1984
  • 1970-1974  (162)
  • 1972  (162)
  • Biochemistry and Biotechnology  (89)
  • Rat  (73)
  • Nuclear reactions
  • 1
    ISSN: 1432-2013
    Keywords: Diphosphate ; Rat ; Vitamin D Metabolism ; Intestinal Calcium ; Absorption ; Bone Mineralization ; Renal Functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The metabolism and the organ distribution of double labelled vitamin D3 (1,2-3H-4-14C-cholecalciferol) has been studied in rats in which the bone mineralization and the intestinal calcium absorption have been inhibited by a large pose (10 mg P/kg s.c. for 7–14 days) of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP). The most striking difference found was a reduced accumulation of radioactive cholecalciferol and its metabolites in the kidney of EHDP-treated rats. It is unlikely that this effect was due to an unspecific alteration of the functional renal tissue since blood urea, glomerular filtration rate and renal plasm a flow remained unaltered by this dose of EHDP. The EHDP-treated rats were able to form the metabolite eluted with peak IV of the silicic acid chromatographic system, that is 25-hydroxycholecalciferol. In these vitamin D repleted rats fed a high calcium diet, the tritium deficient metabolite eluted with peak V (1,25-dihydroxycholecalciferol) was only found in the intestinal mucosa of both control and EHDP groups three days after the injection of radioactive cholecalciferol, and this in a very small amount. Therefore no definitive conclusion can be drawn as to a possible interference of EHDP treatment on the production of 1,25-dihydroxycholecalciferol. The change in the renal metabolism of vitamin D in rats treated with a rachitogenic dose of EHDP may be caused by the modifications of the calcium metabolism brought about by the diphosphonate. Its relation, if any, with the decreased calcium absorption remains to be established.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 272 (1972), S. 369-377 
    ISSN: 1432-1912
    Keywords: Trimethoprim ; Placental Transfer ; Distribution ; Elimination ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After a single i.v. administration of 50 mg/kg of Trimethoprim (TM) to rats in late pregnancy, a diffusion equilibrium of the folic acid inhibitor in the foetal organs is reached after 30–60 min. The TM levels in maternal as well as in foetal organs can have an inhibitory effect on folic acid reductase activity. The elimination of TM is lower in pregnant than in non-pregnant animals. The TM elimination of the foeti is dependent on the elimination capacity of the mother. Three-days-old rats eliminate TM some four times slower than mature animals owing to their reduced kidney development.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 272 (1972), S. 417-436 
    ISSN: 1432-1912
    Keywords: Intestinal Blood Flow ; Instestinal Absorption ; Tritiated Water-Solvent Drag ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Jejunal loops of anaesthetized rats were perfused with hypo-, iso-, and hypertonic buffered solutions containing tritiated water. The blood flow, the disapperance rate (from the intestinal lumen), and the appearance rate (in the intestinal venous blood) were determined simultaneously. 2. A decrease of the blood flow from about 1.7 to 0.2 ml min−1g−1 wet tissue weight diminished the appearance and disappearance rate of tritiated water. An increase of the blood flow caused the reversed results. The appearance rate was almost completely determined by the blood flow indicating that the intestinal absorption of tritiated water is blood flow limited. Therefore the absorption rate of tritiated water characterizes badly the diffusive water permeability of the intestinal epithelium. 3. A water net flux directed towards the blood accelerated and towards the intestinal lumen retarded the intestinal absorption of tritiated water at low, intermediate, and high blood flow values. 4. The data were analysed by a modified four-compartment-model considering the variation of blood flow and water net flux. The water net flux influences the absorption of tritiated water during the penetration through the epithelium by solvent drag (sieving coefficient 1-σ=1.54±0.19) as well as by changing the blood flow rate through capillaries near the epithelium.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 274 (1972), S. 357-374 
    ISSN: 1432-1912
    Keywords: Intestinal Blood Flow ; Blood-to-Lumen Flux ; Tritiated Water ; Solvent Drag ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Anaesthetized rats were loaded with tritiated water and a jejunal loop was perfused with hypo-, iso-, and hypertonic buffered saline solutions. The blood flow, the disappearance rate (from the blood), and the appearance rate (in the intestinal lumen) were determined simultaneously. 2. A decrease of the blood flow from about 1.7 to 0.2 ml min−1g−1 wet tissue weight diminished both the appearance rate and the disappearance rate of tritiated water. An increase of the blood flow caused the reversed results; however, at high blood flow the appearance and disappearance rate did not reach the value measured in the experiments with decreasing blood flow. 3. A water net flux directed towards the blood retarded and towards the intestinal lumen accelerated the blood-to-lumen flux of tritiated water at low, intermediate, and high blood flow values. 4. The data were analysed by a modified four-compartment-model considering the variation of blood flow and water net flux. The water net flux influences the blood-to-lumen flux of tritiated water by solvent drag during the penetration through the epithelium and by changing the luminal concentration (e.g. dilution) as well as the blood flow rate in the capillaries near the epithelium.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 273 (1972), S. 352-365 
    ISSN: 1432-1912
    Keywords: Calcium Transport ; Small Intestine ; Rat ; in vitro ; in vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intestinal calcium (Ca) transport was studied in the rat jejunum by the in vitro perfusion technique of Fisher and Parsons and in the tied loop in vivo. Mucosal uptake and absorption of Ca was examined under the following conditions: rising intraluminal Ca-concentrations (0.5–128 meq/l); inhibition of energy dependent metabolism (2,4-dinitrophenol, N2, low temperature); net water flow, out of or into the intestinal lumen; addition of strontium (Sr); pretreatment with low Ca-diet and with 6-methyl-prednisolone. The concentration-dependent Ca absorption curve rose steeply at low Ca-concentrations but changed to a slowly rising straight line above 16 meq/l Ca++. In contrast, Ca uptake into the intestinal wall was directly related to Ca concentration, was linear from the beginning and paralleled the straight part of the absorption curve. Ca absorption was decreased by inhibition of energy dependent metabolism, addition of Sr and pretreatment with prednisolone. Pretreatment with low Ca diet increased Ca absorption and direction of net water flow (“solvent drag”) had no effect on it. Mucosal uptake of Ca was similar to Ca absorption except that metabolic inhibition increased Ca uptake but decreased Ca absorption. These results are compatible with the concept of a passive mucosal uptake and of an active absorption of Ca at low intraluminal Ca concentrations with additional passive component at high Ca concentrations.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 274 (1972), S. 91-106 
    ISSN: 1432-1912
    Keywords: Choline ; Blood-Brain-Barrier ; Brain ; Rat ; Lecithin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the rat brain the concentration of choline increases with a velocity of 20.5 nMol/g×min immediately after decapitation. This is not due to postmortal disintegration of the tissue but to persisting biochemical reactions in the absence of blood flow. This rise of choline must be considered if the concentration of choline in the living animal is to be established. Taking this fact into account one arrives at a value of 27.5±1.7 nMol Choline/g wet weight. From the arterio-venous difference of choline concentrations it has been postulated that there is an efflux of 7.2±1.5 nMol/g×min from the brain into the blood. After i.v. injection of labelled choline the peak of the specific radioactivity of choline in the brain is reached in less than 1 min but amounts to only one tenth of the specific activity of choline in blood-plasma. The specific activities in both compartments decline in parallel. Thus it can be concluded a) that choline penetrates easily through the blood-brain barrier, but the concentration gradient is directed from brain to blood; and b) that choline is continuously formed in the brain, which process permanently dilutes the quantity of labelled choline and prevents the specific activities in blood and brain from becoming equal. The calculations of turnover-rates in the different reactions leading to the choline containing glycerophosphatides are based on the data obtained. On the basis of these findings it is proposed that in the brain phosphorylated derivatives of ethanolamine (phosphorylethanolamine, cytidinediphosphate-ethanolamine) can be methylated to form the respective choline derivatives.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 238-251 
    ISSN: 1432-0827
    Keywords: Growth ; Bone ; Rat ; Tetracycline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La vitesse de croissance normale en longueur de la métaphyse proximale du tibia est déterminée chez le rat Sprague-Dawley entre les âges de 20 et 100 jours, en utilisant la méthode à la tétracycline. Le taux de croissance ne varie que légèrement dans les groupes d'âges différents. Il est plus élevé chez les animaux jeunes et décroit considérablement en fonction de l'augmentation de l'âge. Les rats mâles présentent une croissance plus élevée que les femelles. Cette étude a pour but de mettre au point une méthode permettant de déterminer les facteurs expérimentaux, liés à la croissance en longueur du rat.
    Abstract: Zusammenfassung Die normale Längenwachstums-Geschwindigkeit der proximalen Wachstumsplatte der Tibia wurde bei Sprague-Dawley-Ratten in einem Alter zwischen 20 und 100 Tagen mittels der Tetracyclinmethode gemessen. Die Wachstumsgeschwindigkeit variierte nur wenig innerhalb der einzelnen Altersgruppen. Die Geschwindigkeit war bei jungen Tieren am höchsten und nahm mit zunehmendem Alter beträchtlich ab. Männliche Ratten wuchsen schneller als weibliche. Diese Arbeit dient als Grundlage, um die experimentelle Beeinflussung des Längenwachstums der Ratte abschätzen zu können.
    Notes: Abstract The rate of normal growth in length from the proximal growth plate of the tibia in the Sprague-Dawley rat was measured between 20 and 100 days of age using the tetracycline method. The growth rate varied only slightly within different age groups. The rate was highest in young animals and decreased considerably with increasing age. Male rats grew faster than female. This study is intended to provide a base for an evaluation of experimental influence on the growth in length of the rat.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 30 (1972), S. 29-38 
    ISSN: 1432-0738
    Keywords: Dichlorvos ; Teratology ; Inhalation ; Rat ; Rabbit ; Dichlorvos ; Teratologie ; Inhalation ; Ratte ; Kaninchen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An Kaninchen und Ratten wurde die teratogene Wirkung von inhaliertem Dichlorvos untersucht. Im Versuch waren primipare Kaninchenweibchen der Rasse “Dutch” mit einem Anfangsgewicht von 2 bis 3 kg und primipare Rattenweibchen vom Stamm “Carworth Farm E“ mit einem Anfangsgewicht von 200 bis 300 g. Die Tiere wurden während der gesamten Trächtigkeit folgenden Konzentrationen in der Atemluft ausgesetzt: 0,25, 1,25 und 6,25 μg Dichlorvos pro Liter Luft. Ein zusätzliches Experiment am Kaninchen wurde mit 2 und 4 μg Dichlorvos pro Liter Luft durchgeführt. Die Behandlung wirkte weder beim Kaninchen noch bei der Ratte teratogen. Selbst Konzentrationen, die für die Kaninchen tödlich waren, und die eine deutliche Cholinesterasehemmung in Plasma, Erythrocyten und Gehirn der Ratten und Kaninchen hervorriefen, wurden ohne Schädigung für die Feten vertragen.
    Notes: Abstract The teratogenic potential of inhaled dichlorvos vapour for rabbits and rats was investigated on the offspring of primiparous female Dutch rabbits weighing 2 to 3 kg and primiparous female Carworth E strain rats weighing 200 to 300 g. The animals were exposed throughout pregnancy at concentrations of 0.25, 1.25 and 6.25 μg dichlorvos per litre of air. In an additional experiment pregnant rabbits were exposed to concentrations of 2 and 4 μg dichlorvos per litre of air. The results gave no indication that dichlorvos vapour is teratogenic in rabbits or rats even at exposure concentrations resulting in maternal deaths in rabbits, and causing depression of plasma, erythrocyte and brain cholinesterase activities in pregnant animals of both species.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 30 (1972), S. 9-18 
    ISSN: 1432-0738
    Keywords: 2,2-Dichlorvinyl Dimethyl Phosphate ; Dichlorvos ; Vapona ; Metabolism ; Man ; Rat ; Mouse ; Hamster ; 2,2-Dichlorvinyl-dimethylphosphat ; Dichlorvos ; Vapona® ; Stoffwechsel ; Mensch ; Ratte ; Maus ; Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An Mäusen und Hamstern wurde die Exkretion und Retention der Radioaktivität nach Fütterung mit [1-14C-Vinyl]-Dichlorvos bestimmt. Außerdem wurde beim Menschen die Exkretion und Exhalation gemessen und die erhaltenen Werte mit den tierexperimentellen Daten von Rattenversuchen verglichen. Die Ergebnisse zeigen einen schnellen Stoffwechsel von Dichlorvos bei allen vier untersuchten Species. Die Dealkylierung zu Desmethyldichlorvos spielt bei der Biotransformation eine untergeordnete Rolle. Eine gewisse Ausnahme zeigen die Mäuse, bei denen 18,5 % der zugeführten Radioaktivität als Desmethyldichlorvos aufgefunden werden konnte. Bei allen Species kam es zu einer hydrolytischen Spaltung zu Dichloracetaldehyd, der weiter zu Dichloraetbanol reduziert wird. Der weitere Weg führt über die Ausscheidung als Glucuronid mit dem Harn. Ein Teil wird dechloriert und das14C-Atom als14CO2 oder14C-Hippursäure im Harn ausgeschieden. Im menschlichen Harn konnte Dichloraethanol nach Inkubation mitβ-Glucuronidase nachgewiesen werden, wenn hohe Dichlorvoskonzentrationen (38 μg/l) eingeatmet wurden. Auf dieser Basis könnte eine Überwachungsmethode gegen die Inhalation von zu hohen Dichlorvoskonzentrationen ausgearbeitet werden.
    Notes: Abstract The routes of excretion and retention of radioactivity following the ingestion of [1-14C-vinyl]dichlorvos by mice and hamsters have been determined. The excretion of radioactivity in urine and exhaled air of man has also been measured. The data have been compared with those for rats. The results indicate that metabolism is rapid in the four species. Dealkylation to desmethyldichlorvos is a minor route of biotransformation, except in the mouse, where desmethyldichlorvos constitutes at least 18.5 % of the administered radioactivity. Hydrolytic metabolism of dichlorvos occurs in all species and leads presumably to dichloroacetaldehyde which is further metabolized by (i) reduction to dichloroethanol and excretion in the urine as the glucuronide and (ii) dechlorination followed by incorporation of the carbon atoms into endogenous biosyntheses and excretion as [14C]carbon dioxide and [14C]hippuric acid in the urine. Dichloroethanol can be detected inβ-glucuronidase-treated urine after exposure of a human subject to high air concentrations (38 μg/l) of non-radioactive dichlorvos. This may form the basis of a method of monitoring the exposure of humans to high concentrations of dichlorvos.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 28 (1972), S. 39-45 
    ISSN: 1432-0738
    Keywords: Ferrihexacyanoferrate (II) ; Rat ; Thallium ; Toxicity ; Metabolism ; Ferrihexacyanoferrat(II) ; Ratte ; Thllium ; Toxicität ; Stoffwechsel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Verabfolgung einer 2% igen kolloidalen Lösung von Ferrihexacyanoferrat (II) (FHCF) als Trinkwasser erhöht bei der Ratte die Ausscheidungsrate von intravenös injiziertem Tl2SO4 (mit 204Tl markiert) aus Leber, Nieren und Muskulatur auf das 2,8fache. Dieser Effekt ist zeitunabhängig. Die LD 50/30 d von intravenös injiziertem Tl2SO4 wird durch FHCF-Behandlung um das 2,3fache erhöht. Für diesen Schutzeffekt ist allerdings nur das während der ersten 24 Std verabfolgte FHCF verantwortlich. Diese Befunde weisen darauf hin, daß die Schäden bei der akuten Tl-Intoxikation sehr schnell irreversibel werden.
    Notes: Abstract The administration of a 2% colloidal solution of ferrihexacyano ferrate (II) (FHCF) as drinking water increases in the rat the excretion of intravenously injected Tl2SO4 (labelled by 204Tl) from liver, kidneys and muscles by a factor of 2.8. This effect is independant of time. FHCF-treatment increases the LD 50/30 d of intravenously injected Tl2SO4 by a factor of 2.3. This protection, however, is provided by FHCF only if administered during the first 24 hours. These findings suggest that the damage resulting from acute Tl-intoxication quickly becomes irreversible.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 137 (1972), S. 301-316 
    ISSN: 1432-0568
    Keywords: Monoamines ; Brain ; Ontogeny ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The early ontogeny of the monoamine neuron systems in the rat brain has been analysed using Falck-Hillarp fluorescence histochemistry. Serial sagittal sections of embryos with a crown rump length between 7 and 13 mm, approximately corresponding to gestational days 12 to 15 were obtained from mothers treated with a monoamine oxidase inhibitor given in order to increase the monoamine levels of the embryos. 5-hydroxytryptamine (5-HT)-neurons made their first appearance in the 8 mm embryo, dopamine (DA)-neurons in the 9 mm embryo, and noradrenaline (NA)-neurons in the 11 mm embryo. Small, rounded, weakly fluorescent cell bodies forming sparse aggregations appeared first. Fluorescent processes of two types soon appeared. Short processes from the cell bodies were running perpendicular to the long axis of the brain stem within the cell groups, while long slender axon bundles could be traced ascending through the met- and mesencephalon and into the prosencephalon as well as descending in the myelencephalon andspinal cord. In the 12 mm embryo the primordial DA cell formation of the substantia nigra with its striatal projections, the 5-HT neuron formations of the caudal mesencephalon, met- and myelencephalon as well as the NA neurons of the met- and myelencephalon are relatively well developed. It is concluded that the monoamine-neurons develop mechanisms for synthesis and storage of amines at a very early stage during ontogeny, thus recapitulating the phylogeny of these old systems. Likewise, monoamine oxidase is present early. The presence of neurotransmitters specifying the different developing neurons long before development of their nerve terminal areas and therefore before the establishment of normal synaptic function may indicate a role of these substances during ontogeny other than transmission of nerve impulses.
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  • 12
    ISSN: 1432-0568
    Keywords: Rat ; Cold ; Pineal gland ; Synaptic vesicles ; Zinc iodide-osmium tetroxide (ZIO) reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In den synaptischen Bläschen der Nervenendigungen der Epiphyse von Ratten, welche 2 und 4 Tage einer Temperatur von −6° bis −8°C ausgesetzt worden waren, hat man eine signifikante Vermehrung des Zinkjodid-Osmiumtetroxyd (ZIO) reaktiven Materials festgestellt. Der durchschnittliche Durchmesser der ZIO-positiven synaptischen Vesiculae betrug bei den Kontrollratten 234 Å und bei den Ratten, welche 2 und 4 Tage unter der Kälte gelebt hatten, 380 Å, bzw. 379 Å. Die ZIO-Reaktion war bei den Kontrollratten in 49,3% der synaptischen Vesiculae positiv, nach zweitägiger Kälteeinwirkung waren 58,7% und nach viertägiger Kälteeinwirkung 72,1% der synaptischen Vesiculae ZIO-positiv. Auf Grund der vorliegenden Arbeit war es jedoch nicht möglich zu entscheiden, ob die Vermehrung des ZIO-reaktiven Materials mit einer gleichzeitigen Zunahme der biogenen Amine verbunden ist.
    Notes: Summary In the synaptic vesicles of pineal nerve endings of Wistar rats exposed for 2 and 4 days to a temperature of −6° to −8° C, a significant increase of the zinc iodide-osmium tetroxide (ZIO) reactive material was observed. The mean diameter of ZIO reactive synaptic vesicles of control rats was 234 Å; in rats exposed to cold for 2 and 4 days it was 380 Å, respectively 379 Å. In control rats the ZIO reaction was positive in 49,3% of the synaptic vesicles. The reactivity increased to 58,7% in rats exposed to cold for 2 days, and to 72,1% in rats exposed to cold for 4 days. However, the results of the present study do not permit to conclude if an increase of ZIO reactive material is accompanied by a simultaneuos increase of biogenic amines.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 137 (1972), S. 1-29 
    ISSN: 1432-0568
    Keywords: Corticotropin-Releasing Factor ; Median eminence ; Rat ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In der Zona externa infundibuli der normalen Ratte kommen geringe Mengen „Gomori-positiver” Granula vor. Nach bilateraler Adrenalektomie erfolgt eine Vermehrung der Granula, die sich durch Gabe von Hydrocortison einschränken oder verhindern läßt. Dieser Befund hat zu der Annahme geführt, daß die Granula das morphologische Äquivalent des Corticotropin-releasing factor (CRF) darstellen. Morphometrische Untersuchungen an 160 weiblichen Wistarratten zeigen, daß die Menge der nach bilateraler Adrenalektomie in der Zona externa infundibuli nachweisbaren „Gomori-positive” Granula von der postoperative Überlebensdauer abhängt. Die Granulamenge nimmt zunächst bis zum 14. Tag p.o. zu und fällt dann wieder ab. Substitution bilateral adrenalektomierter Ratten mit Hydrocortisonacetat-Kristallsuspension bewirkt eine dosisabhängige Verminderung der Granulamenge, wenn die Behandlung am Operationstag begonnen wird. Applikation von Hydrocortisonacetat-Kristallsuspension vom 14.–21. Tag p.o. führt dagegen zu einer gesteigerten Granulavermehrung. Auch bei stärkster Vermehrung sind die Granula stets nur im Infundibulum und nicht in anderen Bereichen des Hypothalamus nachweisbar. Sie besitzen bei bilateral adrenalektomierten Tieren ein charakteristisches Verteilungsmuster mit besonders hohen Konzentrationen in den paramedianen Abschnitten des rostralen Infundibulumdrittels. Aus der Art und Weise ihrer Verteilung ist zu vermuten, daß die Granula 2 Nervenfaserzügen angehören und ein Neurosekret darstellen. Nach den vorliegenden Untersuchungen besteht zwischen dem Verhalten der „Gomori-positiven” Granula in der Zona externa infundibuli und dem aus pharmakologischen Untersuchungen bekannten Verhalten des Corticotropin-releasing factor eine weitgehende Parallelität. Sie legt nahe, die Menge der Granula als Parameter der CRF-Aktivität zu verwenden.
    Notes: Summary In the zona externa infundibuli (outer layer of the median eminence) of the normal rat a minute number of “Gomori-positive” granules can be detected. Following bilateral adrenalectomy their number increases. This augmentation can be restricted or inhibited by administration of hydrocortisone, a finding, which has led to the assumption that the granules are the morphological equivalent of the corticotropin-releasing factor (CRF). Morphometrical studies on 160 female Wistar rats show that following bilateral adrenalectomy the quantity of “Gomori-positive” granules is dependent on the length of the post-operative survival period. Up to the 14th day p.o. the quantity of granules increases; from then on it diminishes. Substitution of bilaterally adrenalectomized rats with hydrocortisone acetate crystal suspension results in a dose-dependent decrease in the quantity of granules if treatment is begun on the day of operation. In contrast, administration of hydrocortisone acetate crystal suspension from the 14th to the 21st day p.o. results in increased augmentation of the granules. Even when maximum augmentation of the granules is reached, they are invariably found only in the infundibulum and not in other regions of the hypothalamus. In animals that have been subjected to bilateral adrenalectomy, the granules show a characteristic pattern of distribution, with particularly high concentrations in the paramedian parts of the rostral third of the infundibulum. The manner in which the granules are distributed suggests that they are a neurosecretory substance localized in two fibre tracts. The present study points to a close parallelism between the behaviour of the “Gomori-positive” granules in the zona externa infundibuli and that of the corticotropin-releasing factor as revealed by pharmacological investigations. It would seem that the quantity of granules can be used as a parameter of CRF activity.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 138 (1972), S. 155-165 
    ISSN: 1432-0568
    Keywords: Cerebellum ; Neurogenesis ; Autoradiography ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Time of origin of various neuronal elements in the cerebellum of rat was established with the aid of tritiated-thymidine-autoradiography. The earliest nerve cells to form were the Purkinje cells, and they came into existence on days 15 and 16 of gestation. Interstitial nerve cells had their genesis on days 15, 16, 17 and 18, and the marginal cells on day 16 of the embryonic development. The Golgi cells were found to come into existence on days 17, 18 and 19 of gestation. On day 21 of gestation a number of small-medium-sized nerve cells, which were smaller than the Golgi cells but larger than the granule cells, were seen to come into existence. Finally, the earliest stock of granule, basket and stellate cells, primarily in the nodulus, flocculus and para-flocculus, were observed to have been formed on the day 21 of embryogenesis.
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  • 15
    Electronic Resource
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    Archives of toxicology 29 (1972), S. 39-49 
    ISSN: 1432-0738
    Keywords: Mouse ; Rat ; Brain ; Light-Dark-Programming ; Circadian ; Toxicity Rhythms ; Acetylcholine ; Pilocarpine ; Oxotremorine ; Carbachol ; Physostigmine ; Neostigmine ; Atropine ; Scopolamine ; Atropine Methyl Nitrate ; Maus ; Ratten ; Gehirn ; Beleuchtungsprogramm ; Circadianer Toxicitätsrhythmus ; Acetylcholin ; Piloearpin ; Oxotremorin ; Carbachol ; Physostigmin ; Neostigmin ; Atropin ; Scopolamin ; Atropin-methylnitrat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Adaptation an ein Licht-Dunkelprogramm (8.00 bis 20.00 Licht, 20.00 bis 8.00 Dunkelheit) wurde der Acetylcholingehalt (ACh) im Mittelhirn und N. caudatus von Ratten sowie im Gesamthirn von Mäusen bestimmt. Die höchsten ACh-Konzentrationen wurden bei Ratten um 24.00 gefunden; die höchsten ACh-Werte bei der Maus waren nicht signifikant von den Konzentrationen um 24.00 und 12.00 verschieden. Signifikante ACh-Minima traten im Mittelhirn der Ratte um 12.00, im N. caudatus sowie im Mäusegehirn um 18.00 Uhr auf. Während der Dunkelperiode wurde die größte Toxicität gegenüber i.v. bzw. i.p. injiziertem ACh bei Mäusen gefunden. Ähnliche zeitliche Unterschiede ergaben sich für Neostigmin, Pilocarpin und Oxytremorin. Die Toxicität von Carbachol zeigte Maxima bei 12.00 und 24.00. Für Physostigmin, einen CholinesteraseHemmstoff mit einem tertiären Stickstoff, lagen sowohl die Toxicitätsmaxima als auch die Toxicitätsminima in der Dunkelperiode. Die rhythmische Schwankung der Toxicität von i.p. verabfolgtem Atropin verhielt sich umgekehrt wie die der Cholinomimetica (außer Carbachol). Auch nach i.v. Applikation von Scopolamin und N-Methylatropin war ein entsprechender rhythmischer Einfluß auf die Toxicität nachweisbar. Die Vorbehandlung mit N-Methylatropin schwächte die Toxicität zwar ab, der Toxicitätsrhythmus gegenüber ACh und Physostigmin war aber nicht verändert. Die Toxicität von Cholinomimetica zeigt ein Maximum während der höchsten ACh-Konzentrationen im Gehirn und der höchsten Stoffwechselaktivität. Bei den anticholinergen Substanzen zeigte sich ein umgekehrtes Verhältnis. Die Beziehungen zum zentralen ACh-Gehalt sind unklar.
    Notes: Abstract Acetylcholine (ACh) levels were determined in rat midbrain and caudate nucleus and mouse whole brain in mature animals adapted 3 weeks to a programmed lighting schedule (08:00 to 20:00 h light; 20:00 to 08:00 dark). Peak ACh levels in the rat occurred at 24:00 h; in the mouse the peak at 06:00 h did not differ significantly from values obtained at 24:00 and 12:00 h. Significant trough values occurred at 12:00 h in rat midbrain and at 18:00h in rat caudate nucleus and mouse brain. In mice toxicity of I.V. and I.P. administered ACh is maximal during the dark. Neostigmine, pilocarpine and oxotremorine have toxicity patterns similar to ACh. Carbachol toxicity peaked at 12:00 and 24:00 h. With physostigmine, a tertiary anticholinesterase, peak and trough occurred during the dark. The atropine (I.P.) toxicity rhythm is a mirror image of the cholinomimetic rhythm (except for carbachol). I.V. scopolamine and atropine methyl nitrate patterns resemble atropine's but are less clear-cut. Atropine methyl nitrate pretreatment reduced ACh and physostigmine toxicity but did not alter the overall pattern. Cholinomimetic toxicity and brain ACh patterns are similar, peaking when metabolic activity is maximal. An inverse relationship holds for the anticholinergic drugs. The relationship to central ACh is uncertain.
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  • 16
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    Experimental brain research 15 (1972), S. 29-38 
    ISSN: 1432-1106
    Keywords: Ventromedial hypothalamus ; Single units ; Spontaneous and stimulated activity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between mean firing rate and activity pattern was studied in 177 neurons in the ventromedial hypothalamus of rats immobilized by Remyolan. Stationary epochs of spontaneous or stimulated activity containing at least 512 interspike intervals were analyzed with the LINC computer. The most frequently encountered interval histograms (IHs) were of the exponential (35%) or gamma 2 (25%) type. The IH shape remained unchanged even if the average firing rate was varied over a wide range (from 20/sec to 2/sec) by polarization through the recording microelectrode (2–5 nA, 1–10 min) or by intracarotid injection of glucose (0.1 ml, 10–25%). The coefficient of variation (CV = SD/ mean interval) was 1.03 for the spontaneous and 0.90 or 0.95 for the activity influenced by polarization or glucose, respectively. Since according to other studies sensory stimulation decreases CV by reorganization of the synaptic input, it is suggested that polarization and glucose affect predominantly the postsynaptic elements without significantly changing the presynaptic activity pattern.
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  • 17
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    Acta neuropathologica 20 (1972), S. 248-257 
    ISSN: 1432-0533
    Keywords: Experimental CNS Tumours ; N-Nitrosomethylurea ; Ethylnitrosourea ; Cell Culture ; Clonal Growth ; Aggregation Pattern ; Transplantation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two sarcomas, one neurosarcoma and one polymorphous tumour of uncertain classification of the central nervous system of the rat induced by N-nitrosomethylurea or ethylnitrosourea were the source of 14 clones. The cytomorphology and the aggregation pattern of the clonesin vitro are described. The malignancy and histology were checked by homologous transplantation. All the clones formed sarcoma-like structuresin vivo, but it was difficult to decide whether these neoplasias were real sarcomas or very dedifferentiated glial tumours. The differences in cytology observedin vitro were greater than the histological differencesin vivo.
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  • 18
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    Acta neuropathologica 22 (1972), S. 269-271 
    ISSN: 1432-0533
    Keywords: l-DOPA ; Neoplasm, Striatal ; Motor Behavior ; Rat ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After administration ofl-DOPA to a rat with a unilateral striatal neoplasm of the nucleus caudatus-putamen, postural asymmetries and rotating behavior were observed. These observations are discussed in relation to the activity of catecholamines within the central nervous system.
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  • 19
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    Psychopharmacology 24 (1972), S. 449-455 
    ISSN: 1432-2072
    Keywords: Avoidance and Acquisition ; Methamphetamine ; Discrimination Learning ; CNS Stimulants ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Avoidance responses, extra responses (on avoidance lever) and wrong lever responses were measured in naive rats acquiring a discriminated avoidance in a 2 lever Skinner box, 30 min after methamphetamine (0.25, 0.5 and 1.0 mg/kg). The smallest dose was ineffective; 0.5 and 1.0 mg/kg significantly increased the number of avoidance responses. This increase was not associated with a significant increase in the two other responses studied. The progressive increase (from the first to second part of the acquisition session) in avoidance responses was not accompanied by a parallel increase in the other responses. The position discrimination and the discrimination of the presence or absence of the conditioned stimulus was observed to be better in the drug groups.
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  • 20
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    Psychopharmacology 26 (1972), S. 195-200 
    ISSN: 1432-2072
    Keywords: Forced Motility ; Motor Activity ; Brain Noradrenaline and 5-Hydroxytryptamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The levels of 5-HT and 5-HIAA in the rat brain were measured after 1, 6, 24 and 36 h of forced motility in a treadwheel. The results showed that 5-HT metabolism had already increased in the forebrain after 1 h of exercise but later also increased in the brain stem, especially in the mesencephalon-pons-medulla regions. These changes had almost entirely disappeared after 50 min of rest. The NA levels with and without monoamine oxidase inhibitor were measured in animals after 36 h of forced motility. The results indicated an increase in NA metabolism in the brain stem.
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  • 21
    ISSN: 1432-2072
    Keywords: Agressive Behaviour ; Apomorphine ; Testosterone ; Testes ; Hypophysis ; Adrenal Glands ; Thyroid ; Castration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The weights of testes, prostates, adrenals, thymus and the pituitary of rats with apomorphine induced aggressiveness did not differ from those without aggressiveness. Postpubertal castration, adrenalectomy or thyroidectomy did not reduce the apomorphine induced aggressive behaviour, but a considerable reduction was found after hypophysectomy. Prepubertal castration significantly reduced, but did not completely abolish the proportion of aggressive rats, especially when castration was performed on the 5th day. Prolonged treatment of male, female and castrated rats with high doses of testosterone from the time of weaning increased the proportion of aggressive animals. Less intensive treatment and treatment of adult rats were ineffective.
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  • 22
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    Psychopharmacology 26 (1972), S. 317-320 
    ISSN: 1432-2072
    Keywords: Oxazepam ; Conflict Behavior ; Rat ; Maze
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were tested in a Lashley III maze, the floor of which was heated. The animals had to learn to negotiate it in order to gain access to the unheated goal box. In the early period of training the animals were able to find the goal box rapidly and without error. Their performance then deteriorated, in a particular way which strongly evoked a conflict behavior. This deterioration in performance was progressively reduced by oxazepam administration (8 mg/kg/day).
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  • 23
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    Psychopharmacology 25 (1972), S. 218-228 
    ISSN: 1432-2072
    Keywords: Fighting ; Delta-9-Tetrahydrocannabinol ; Chlordiazepoxide ; Fixed-Interval ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The frequency with which electric shock to the feet elicited fighting in five pairs of albino rats was not altered significantly by intraperitoneal injections of delta-9-tetrahydrocannabinol (THC) in doses ranging from 0.064–6.4 mg/kg, although chlordiazepoxide reduced the frequency of such fighting in a dose-related manner. This finding held true despite manipulations of THC vehicle, injection-test interval, and the previous drug experience of the subjects. In contrast, doses of 4.0 mg/kg produced a striking reduction in lever-pressing maintained by an FI 60″ schedule of food reinforcement.
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  • 24
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    Psychopharmacology 23 (1972), S. 171-179 
    ISSN: 1432-2072
    Keywords: Reserpine ; Neonatal Treatment ; Sexual Behaviour ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate whether reserpine given in the critical period of sexual differentiation of the rat brain affects adult sexual behaviour, female and male rats were given a single injection of reserpine on the fourth day after birth, and their sexual behaviour was tested at maturity. In the 11 consecutive daily tests for spontaneous sexual behaviour the reserpine treated female animals showed fewer regular behavioural and vaginal oestrous cycles than the control animals. 19 % of the reserpinized and none of the control animals had prolonged oestrous behaviour without a coincident prolonged vaginal cycle. The reseptivity quotients of the reserpine treated animals were reduced. In the tests for hormone induced sexual behaviour after ovariectomy no statistically significant differences between the number of animals responding or between the receptivity quotients occurred. The tests for spontaneous sexual behaviour in males showed that the reserpinized animals needed fewer intromissions to ejaculate than the controls. The significance of these findings is discussed.
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  • 25
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    Psychopharmacology 26 (1972), S. 347-360 
    ISSN: 1432-2072
    Keywords: Chronic Nicotine ; Attention Task ; Arousal ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Male, Holtzman rats were trained extensively on an attention task which required them to respond with a single lever-press to a very short, variably presented stimulus for food reinforcement, but which also required them to inhibit inappropriate responses. After performance had stabilized, two groups were treated with either nicotine base (100 Μg/kg, s.c., t.i.d.) or saline for 4 weeks. The groups were crossed-over so that the first received saline and the second nicotine for an additional 4 weeks. A 3-week saline recovery period followed. Rats were tested on the attention task daily through all periods. Analysis of the data indicated that independent of the treatment-order, rats performed more efficiently under nicotine treatment than under saline conditions. The improvement in performance was most notable in the reduction of inappropriate responding during chronic nicotine treatment. The significance of the behavioral changes in relation to proposed nicotine-induced neurophysiological changes and the two-arousal hypothesis are discussed.
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  • 26
    ISSN: 1432-2013
    Keywords: Cardiac Output ; Blood O2 Dissociation Curve ; High Altitude ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In rats adapted to a simulated altitude of 3500 m cardiac output measured at hypoxia by the direct Fick principle was significantly lower than in the control animals (mean values 54.3 ml/min and 69.8 ml/min, resp.). The decrease of cardiac output was accompanied by an increase of arterio-venous O2 difference and a decrease of stroke volume in the adapted rats. It is suggested that the decrease of cardiac output might be related to the increase of hematocrit. The adapted rats also showed higher arterial and mixed-venous O2 content (both at hypoxia) and increased O2 capacity. Arterial O2 saturation of the animals previously exposed to simulated high altitude hypoxia was significantly higher (67.3% as against 61.2% in the controls). The standard O2 dissociation curve showed lower oxygen affinity in the blood of the adapted animals but no physiological advantage concerning the transport of O2 to the tissues was found. In another group of animals the Bohr factor was estimated and no difference was found between rat and human blood.
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  • 27
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    Pflügers Archiv 335 (1972), S. 198-212 
    ISSN: 1432-2013
    Keywords: Intestinal Absorption ; Medium Chain Fatty Acids ; Kinetics ; Active Transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The transport of14C-octanoate by rat small intestine was determined in vitro by a modification of the method of Semenza and Mühlhaupt, and in vivo by using isolated segments or a perfusion technique in conscious rats (Haberichet al., 1968). 2. The absorption capacity of14C-octanoate in the distal ileum was significantly lower than in the proximal jejunum. 3. 14C-octanoate injected into a jejunal segment appeared rapidly in portal venous blood reaching its maximal concentration 4 min after the injection. 4. The transport of octanoate showed a saturation effect with increasing concentrations after an incubation of 4 min. However, with constant concentrations of octanoate in the medium, the transport rate was constant for 8–10 min. A similar saturation effect was also demonstrated in vivo. Values for maximal absorption rate (V max) and the half-saturation constant (K m), calculated from the Lineweaver-Burk plot, were 1.0 μMol/min and 17.7 mM, respectively. 5. Accumulation of octanoate in tissue water was demonstrated. For example, after incubation for 40 min in a medium concentration of 0.1 mM, the tissue/ medium ratio was 2.75:1. 6. Cyanide (2×10−4 M) markedly diminished the absorption rate of octanoate. 7. The absorption of octanoate was competitively inhibited by caproic acid (C6) in vitro. The inhibition constant (K i), calculated from the Dixon plot, was 47 mM. 8. Simultaneous administration of glucose and octanoate in vivo did not affect the absorption rate of the fatty acid. 9. These results suggest that the intestinal absorption of octanoate is an energy-dependant active process.
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  • 28
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    Pflügers Archiv 334 (1972), S. 293-302 
    ISSN: 1432-2013
    Keywords: Lactate Turnover ; l-Lactate14C (U) ; Hypoxaemia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Lactate turnover was measured in 24 anesthetized rats using14C-U-(l) Lactate with the priming dose-infusion technique. 2. 14C Lactate in blood was determined with a specific radio-enzymatic micromethod. 3. Lactate turnover increases with blood lactate concentration in the range 0.5 to 3 mM. In a steady state system this relationship means that a new equilibrium may be achieved at a higher pool level, between lactate production and utilization. 4. Comparing available data in four mammalian species lactate turnover at normal lactate levels was found to be approximately constant when computed on a body surface unit basis.
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  • 29
    ISSN: 1432-2013
    Keywords: Cardiac Hypertrophy ; Diffusion Distance ; High Altitude ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In growing rats adapted to a simulated altitude of 3500 m for about 4 weeks and in their controls the evolution of cardiac ventricular weight was followed. The increase of total ventricular weight found in the adapted animals can be attributed exclusively to the increase of right ventricular weight. In other adapted and control animals cardiac capillary densities, muscle fiber diameter and external capillary radius were estimated and fiber—capillary ratio and diffusion distance were calculated. There was an increase of capillary density together with a decrease of muscle fiber density, fiber-capillary ratio and diffusion distance in the right but not in the left ventricle of the adapted rats. The muscle fiber diameters, however, were larger in both heart ventricles of the rats exposed to a simulated high altitude, especially in the right ventricle. This indicates that true hypertrophy of the muscle fibers is mainly responsible for the increase of right ventricular weight. In the left ventricle, however, a hypertrophy of the muscle fibers together with a decrease of stroma components is demonstrated. The physiological importance of the shorter diffusion distance in the right ventricle of the high altitude adapted rats is discussed and it is suggested that the shorter diffusion distance may help to keep the tissue O2 partial pressure above the critical value, mainly also in extreme situations with high myocardial O2 consumption.
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  • 30
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    Pflügers Archiv 331 (1972), S. 357-364 
    ISSN: 1432-2013
    Keywords: Thoracic Aorta ; Complex Dynamic Young's Modulus ; Age ; Serum Lipids ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 2 groups of male albino rats (wistar-strain), 6 months and 18 months of age, dynamic Young's moduli in longitudinal direction were measured, at 5 different frequencies between 1 and 5 Hz. Each group consisted of 10 animals. Measurements were made at the natural length and at 1.2 times this length. From each animal several serum lipids were determined. It was found that: 1. measured at the natural length and 1.2 times this length, no significant difference of dynamic Young's moduli between both age groups could be demonstrated 2. concerning the dynamic Young's moduli there is significant interaction between stretch level and age 3. retraction was significantly smaller in the old rats than in the young ones 4. the old animals had a significantly higher serum lipid content than the young rats 5. no correlation between serum lipids and Young's moduli could be demonstrated.
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  • 31
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    Pflügers Archiv 337 (1972), S. 71-79 
    ISSN: 1432-2013
    Keywords: Rat ; Hypothalamus ; Prolactin ; LH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Plasma levels of prolactin and LH were measured by radioimmunoassay following electrochemical stimulation of the medial preoptic area (MPO) or the arcuate nucleus (Arc.N.) in pentobarbital anesthetized proestrous rats. Differences in the secretion pattern of prolactin and LH were observed when stimulated by means of acutely or chronically implanted electrodes. Acute implantation and stimulation of the MPO resulted in no change in serum prolactin levels, whereas stimulation by means of chronically implanted electrodes evoked a marked increase in serum prolactin. The general observation was that electrostimulation in the acute experiments causes a less sharp but more prolonged prolactin and LH release from pituitary than stimulation through chronically implanted electrodes.
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  • 32
    ISSN: 1432-2013
    Keywords: Pulmonary Diffusing Capacity ; Alveolar-arterial O2 Pressure Difference ; High Altitude ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Steady-state pulmonary diffusing capacity for CO and alveolar-arterial O2 pressure differences were measured at hypoxia in growing rats adapted to a simulated altitude of 3500 m. The pulmonary diffusing capacity was significantly higher and the alveolar-arterial gradients were significantly lower in the adapted animals as compared with the controls exposed to hypoxia for the first time. The increased diffusing capacity could be explained entirely by the increase of blood O2 and CO capacity whereas the decrease of gradients might be explained by the increase of blood O2 capacity together with an increase of the arterio-venous O2 difference.
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  • 33
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    Journal of neurology 202 (1972), S. 21-36 
    ISSN: 1432-1459
    Keywords: Hydrocephalus, Experimental ; Ethylnitrosourea ; Experimental Hydrocephalus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 25 mg/kg Äthylnitrosoharnstoff wurden am 9 1/2. Tag der Schwangerschaft SD-JCL-Ratten injiziert. Die Feten wurden am Termin excidiert und mit dem Stereomikroskop untersucht. 78% der Feten zeigten einen Hydrocephalus. Die histologische Untersuchung in Stufenschnitten des Gehirns zeigte eine Stenose des Aquädukts ohne subependymale Gliose, ödematöse Plexus chorioidei mit prallgefüllten Gefäßen, spärlichem Bindegewebe und geschwollenen Epithelzellen, Verdünnung der telencephalen Wandungen mit schwach entwickelter granulärer Schicht und in der ependymalen Zone verbleibenden Neuroblasten. Die Entwicklung der jungen Ratten wurde studiert. 75% der neugeborenen Ratten zeigten klinisch gewisse Hinweise auf den Hydrocephalus. Stark betroffene Tiere wurden zunehmend somnolent und/oder gelähmt und starben meist vor Ende der 4. Woche. Der Eiweißgehalt des Liquors war nennenswert vermehrt. Es wurden subdurale, subarachnoidale und intraventrikuläre Blutungen beobachtet und als wahrscheinliche Todesursache angesehen. Die histologische Untersuchung der hydrocephalen Jungtiere ergab eine Abflachung der Ependymzellschicht und pralle Füllung corticaler Gefäße von der 2. Woche an. In späteren Stadien wurde eine Dickenabnahme der periventrikulären weißen Substanz, im besonderen im Bereiche des Occipitalhornes nachgewiesen. Im verdünnten Pallium waren Vacuolenbildungen des perineuralen Gewebes zu sehen, Verbreiterung der Virchow-Robinschen Räume und eine dem Status spongiosus ähnliche Degeneration. Verschiedene Formen ependymaler Wucherung wurden gesehen. Die vorliegende Studie stellt die erste postnatale Beobachtung von transplacentar verursachtem kongenitalem Hydrocephalus in der Ratte dar. Die hier beschriebene Technik erwies sich als einfaches und reproduzierbares Mittel, um einen kongenitalen Hydrocephalus in der Ratte zu erzeugen.
    Notes: Summary SD-JCL rats were injected with 25 mg/kg of ethylnitrosourea on day 9 1/2 of gestation. Fetuses were excised near term and examined under dissecting microscope. 78% of viable fetuses were found to be hydrocephalic. On the histologic study of the serial sections of the brain, a stenosis of the Sylvian aqueduct without subependymal gliosis, edematous choroid plexus with engorged vessels, scanty connective tissue and swollen epithelium, thinning of the telencephalic wall with poorly developed granular layers and the neuroblasts remaining in the ependymal zone, were the characteristic findings in the hydrocephalic fetuses. The natural course of the treated young rats was studied. 75% of the newborn rats showed some clinical evidence of hydrocephalus. Severely affected rats became progressively lethargic and/or paralytic, and died usually before the end of 4th week. Protein content of the cerebrospinal fluid was significantly increased. Subdural, subarachnoid and intraventricular hemorrhages were observed and suspected to be the cause of death. On the histological examination of hydrocephalic youngs, flattening of the ependymal cells and engorgement of the cortical vessels were observed as early as in 2-week-old youngs. In more advanced stages, there was noted the thinning of the periventricular white matter, especially around the occipital horn. The thin pallium showed vacuolization of the perineural tissue, enlargement of the Virchow-Robin space and the status spongiosus-like degeneration. Various types of ependymal proliferation was seen. The present study represents the first postnatal observation of the transplacentally induced congenital hydrocephalus in the rat. The present technique proved to be a simple and reproducible model of producing a congenital hydrocephalus in the rat.
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  • 34
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    Research in experimental medicine 159 (1972), S. 114-123 
    ISSN: 1433-8580
    Keywords: Scalds ; Local cooling ; Rat ; Quantity of leucocytes ; Verbrühung ; Lokale Kühlung ; Ratte ; Verhalten der Leukocyten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Untersuchungen an Ratten ergaben folgende Befunde: 1. Sofortige lokale Kühlung nach der Verbrühung beeinflußt bei der Ratte im untersuchten Zeitraum von 15 Tagen den Verlauf der Erkrankung gemessen am Parameter der Leukocytenzahl. 2. Die Kühlungszeit muß ausreichend lang sein. 3. Die Kühlung muß früh genug einsetzen, beim Versuchstier Ratte innerhalb 5 min nach Verbrühung. 4. Bei verspätetem Kühlungsbeginn läßt sich auch durch Verlängerung der Kühlungsdauer das Verhalten der Leukocytenzahl im Ablauf des Krankheitsgeschehens nach Verbrühung nicht beeinflussen.
    Notes: Summary Following results are obtained in experiments with rats: Immediate local cooling after scald had a significant influence on progress of “burn-disease”. Time for local cooling must be long enough, onset of local cooling early enough. It is not possible to restore the consequences of a late onset by prolongation of cooling.
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  • 35
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 36
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    Biotechnology and Bioengineering 14 (1972), S. 33-42 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The release constant, k, of brewers yeast sonicated at powers up to 200 W at 20 kHz has been shown to be independent of cell concentration up to values of 60 g made up to 100 ml. It is inversely proportional to the volume of the treatment vessel in the range 75 to 450 ml, and almost proportional to the input acoustic power from 60 to 195 acoustic watts. A flow system is described and a relationship linking protein release, flow rate, and the protein release constant, determined from batch experiments, is derived. Good agreement between the theoretical prediction of protein release and experimental results with the flow system was obtained.
    Additional Material: 6 Ill.
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  • 37
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    Biotechnology and Bioengineering 14 (1972), S. 319-330 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bacterial strains were isolated from California coastal areas which showed the ability to oxidize normal paraffins, iso-paraffins, and aromatic hydrocarbons in a synthetic seawater medium. The ability to utilize a particular hydrocarbon was established not only on the basis of visible bacterial growth but also through a chromatographic technique which was standardized and which could define the amount of each hydrocarbon consumed by the bacteria in a mixture. Some of the strains exhibited vigorous hydrocarbon oxidation when exposed to synthetic mixtures of hydrocarbons as well as crude oil. Under conditions of aeration and agitation, mixed cultures could destroy approximately 50% of a South Louisiana crude oil in a period of 48 hr.
    Additional Material: 9 Ill.
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  • 38
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    Biotechnology and Bioengineering 14 (1972), S. 379-390 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cultivation of Corynebacterium hydrocarboclastus, which is capable of synthesizing an extracellular polymer and utilized hydrocarbons, has been reported. Growth studies in shake flasks and fermenters were made to obtain maximum polymer production. Polymer formation was found to be growth associated. The highest level of polymer accumulation was attained after 50-60 hr cultivation in the fermenter and it amounted to approximately 5.5-6 g/liter of fermentation broth. The medium contained initially 2% (v/v) kerosene as a carbon source. The maximum yield obtained corresponds to 37-40% (w/w) of kerosene supplied. At the same time the cell concentration was 10-13 g/liter which represents the yield of 67-87% (w/w). The rate of polymer production in the exponential phase was 0.25 g/liter hr and cell production rate was 0.27 g/liter hr. Sodium nitrate, 0.5%, and yeast extract, 0.3%, (w/w) were the best nigrogen sources for polymer formation. The highest level of polymer produced in broth was 6 g/liter.
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  • 39
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    Biotechnology and Bioengineering 14 (1972), S. 685-714 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Characterization of proteolytic activity in preparations or fermentation broth is accomplished by methods based on a combination of disc electrophoresis and visualization of the activity. The methods permit a direct, comparison with reference preparations. All alkaline proteases studied, including the three subtilisins, were found to consist of several proteolytic components. The zymograms of the subtilisin type preparations show an irregular pattern. At least 14 different components may be observed, belonging to 6 types of mobility pattern, 3 of which could be assigned to the subtilisins. None of the components belongs to the group of metalloproteases. A quite regular pattern is shown by the zymogram of protease preparations produced by the alkalophilic Bacillus strains.A few of the components of the subtilisin preparations Maxatase and protease A were isolated by preparative disc electrophoresis and by disc electrofococusing, allowing a further characterization. Special attention was directed to the determination of properties specific for the application of subtilisins as additives in household detergents. Thermostability in sodium tripolyhosphate solution was found to range from about 10% for one of the minor components to 80% for the main component of Maxatase. Three types of curves representing the effect of pH on the activity were observed. The curve of the main component of Maxatase shows a characteristic shape with a maximum at pH 10.3: with other components lower pH optima were observed. Isoelectric points of the component were found to range from pH 7 to 10.
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  • 40
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    Biotechnology and Bioengineering 14 (1972), S. 1-12 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The validity of regarding the liquid phase in vigorously agitated sparged fermenters during the cultivation of single-celled aerobic microorganisms as essentially homogeneous is examined. Droplet formation from bursting bubbles and physical effects of the spray environment on single-celled microorganisms are discussed. The implications of droplet removal from the head space of fermenters by collision with and drainage down the walls are considered, particularly factors concerned with wall growth above the liquid level in fermenters.
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  • 41
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    Biotechnology and Bioengineering 14 (1972), S. 361-377 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Six soil isolates were grown on a petroleum sulfonate medium and analyzed chromatographically to determine their amino acid composition. The organisms were also examined to determine their growth rate in the petroleum medium, their per cent conversion of hydrocarbon to dry cell mass, their protein content, and their possible use as a food or food supplement. It was found that the isolates varied extensively as to their amino acid composition. Several of the isolates proved to convert the hydrocarbons to cell mass with relative ease. The proteins of four of the isolates appear to be suitable as a good food source, and the protein of one of the remaining isolates appears to be a very good food supplement.
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  • 42
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    Biotechnology and Bioengineering 14 (1972), S. 715-724 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pullulanase (EC 3.2.1.9) prepared from a culture of Acrobacter aerogeneshas been covalently bound to an inert crosslinked copolymer of aerylamide-acrylic acid by using a water-soluble carbodi-imide. The binding yield based on the amount of added pullulanase was 34%. The residual enzymic activity was 43%, of that of free enzyme. Coupling in the presence of the substrate pullulan gave a 5-fold increase in activity over that obtained when substrate was lacking. The effect of different carbodi-imide concentrations on the coupling has been investigated. The isoelectric point of the pullulanase preparation (3.5-4.0) was determined using isoelectric, focusing, in order to find optimal pH conditions for the coupling procedure. The immobilized pullulanase in a packed bed column was used to debranch amylopeetin to low molecular weight amylose.
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  • 43
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    Biotechnology and Bioengineering 14 (1972), S. 857-860 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 44
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of diffusion on the apparent thermal stability of a reversibly or irreversibly denaturable enzyme is examined theoretically when he enzyme is uniformly distributed in a porous solid. If the overall reaction rate is influenced by diffusion through the catalyst, the insolubilized catalyst is shown to yield an apparently more thermally stable enzyme even though the maximal velocity Vm, and the Michaelis constant, Km, are the same for the free and insolubilized forms of enzyme.Brief consideration is given to the experimental conditions needed to clearly demonstrate whether insolubilization does or does not effect the thermal stability of the enzyme.
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  • 45
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    Biotechnology and Bioengineering 14 (1972), S. 447-457 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods for reducing the content of nucleic acid in protein concentrates from disintegrated yeast and microalgae were investigated. Protein concentrates were prepared by acid precipitation of extracted protein after cell wall separation. The influence of alkaline protein extraction on the content of RNA in isoelectrically precipitated protein concentrates was studied. It was found that when a strong decrease in the RNA content was obtained, this was followed by a decrease in the yield of protein concentrate. Protein concentrates were also prepared without cell wall separation by precipitation with different agents after cell disintegration. In the precipitates from microalgae, a RNA reduction was obtained. Precipitation of yeast, protein gave no essential reduction with the precipitants used. Precipitation of yeast protein by heating at an alkaline pH gave a protein concentrate with a low content of RNA. A slightly lower RNA content was obtained when the precipitation was performed in the presence of NaCl. The yield of amino acid nitrogen was 70-80% and the RNA content was 1-2%. A process with precipitation at alkaline pH for the production of microbial protein concentrates with a low content of nucleic acid is suggested.
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  • 46
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    Biotechnology and Bioengineering 14 (1972), S. 499-504 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 47
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    Biotechnology and Bioengineering 14 (1972) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 48
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    Biotechnology and Bioengineering 14 (1972), S. 587-608 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Because of the importance of the drop she distribution and interfacial area of the dispersed liquid phase in hydrocarbon fermentations, experiments were carried out to determine the drop size distribution and the interfacial area during batch fermentations of Candida lipolytica on gas oil and on n-hexadecane dissolved in dewaxed gas oil. The effects of cell concentration and dispersed phase volume fraction on size distribution and interfacial area were investigated. Measurements of interfacial tensions, densities, viscosities, and fatty acid concentrations were also made. The results show that the size distribution is skewed and that the Sauter mean diameter is in the range of 10 to 30 μ. Both the Sauter mean diameter and the interfacial area increased during the course of a batch fermentation; however, they decreased at the end of the fermentation. The interfacial area also increased with inoculum size.
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  • 49
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    Biotechnology and Bioengineering 14 (1972), S. 777-786 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of carbon dioxide-enriched air on the rate of zinc extraction during the microbiological leaching of a, high-grade zinc sulfide concentrate by Thiobacillns ferrooxidans have been studied. Under normal air-aeration conditions, the leach rate is limited initially by the availability of solid substrate surface area per unit volume of leach liquor, then by availability of carbon dioxide. If carbon dioxide-enriched air is supplied, along with excess substrate, the zinc extraction rate increases as the carbon dioxide content increases until some other, as yet unknown, factor becomes limiting.
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  • 50
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    Biotechnology and Bioengineering 14 (1972), S. 843-846 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 51
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    Biotechnology and Bioengineering 14 (1972), S. 847-850 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 52
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    Biotechnology and Bioengineering 14 (1972), S. 861-870 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A gram scale enzymatic synthesis of eight, dinucleoside monophosphates (ApC, ApU, CpC, CpU, GpC, GpU, UpC, and UpU) is described. The synthesis involves a reaction between the appropriate ribonucleoside-2′,3′-cyclie phosphates and cytidine or uridine in the presence of ribonuelease from Aspergillus clavatus at 30°C. The enzyme is removed from the reaction mixture by chromatography on Bio-Gel P-4, and the dinucleoside monophosphate is further purified by chromatography on a DEAE-Sephadex A-25, column.A procedure for the large scale preparation of the ribonuclease from Aspergillus clavatus is also described.
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  • 53
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    Biotechnology and Bioengineering 14 (1972), S. 975-984 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The preparation of a water-insoluble derivative of glucose oxidase by covalent coupling to nickel on silica alumina is described. The catalyst has superior physical characteristics to conventional immobilized enzymes; although its activity and stability are now comparable to conventional catalysts, potential for significant further improvements has been demonstrated.
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  • 54
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    Biotechnology and Bioengineering 14 (1972), S. 43-59 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this work, a radiometric method is used for the determination of the oil drop size distribution in agitated hydrocarbon-water systems. The influence of the counter position, the oil concentration, and the rotation speed of impeller were studied. An experimental parameter is proposed for the definition of the drop size distribution. It was observed that an unsymmetrical distribution represents the drop size distribution better than the normal distribution law.
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  • 55
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We developed an efficient and simple method for RNase extraction from Candida lipolytica cells which consists of predrying the cells with solvents and incubating them for 8 to 15 hr at 37 to 45°C in a slightly acid buffer which contains EDTA or salts. This method is called Solvent Dehydration Buffer Extraction (SDBE) procedure. Predrying with acetone or ethanol, or by lyophilization, followed by washing with acetone or ethylacetate gives the most efficient RNase extraction. The yield and specific activity obtained by this extraction procedure are higher than by any other method examined. An apparent 1.5- to 2.0-fold activation of RNase occurred during the SDBE process. Activation of RNase in homogenates obtained by grinding fresh cells is also observed with EDTA or acetate buffer. The SDBE procedure works efficiently regardless of growth phase for Candida lipolytica, and works also with other Candida yeasts.
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  • 56
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    Biotechnology and Bioengineering 14 (1972), S. 411-436 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Presently empirical expressions, especially the Monod equation, are used to quantitatively relate microbial growth rate to limiting substrate concentration in the solution. In this paper microbial growth is postulated to occur by a mechanism involving a mass transfer or assimilation process. The assimilation process is assumed to be substrate mass transfer limited and hence proportional to the limiting substrate concentration. The ingestion is assumed independent of limiting substrate concentration and only dependent upon internal reaction rates. The quantitative relationship between limiting substrate and microbial growth rate resulting from this mechanism is developed. Under certain limiting conditions this expression is shown to reduce to the Monod equation and under other conditions it reduces to the Lotka-Volterra relationship. This mechanism is applied to batch and continuous cultures and the results obtained are compared quantitatively with experiment.
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  • 57
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    Biotechnology and Bioengineering 14 (1972), S. 493-497 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 58
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    Biotechnology and Bioengineering 14 (1972), S. 509-513 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 59
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    Biotechnology and Bioengineering 14 (1972), S. 571-586 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of dispersed phase volume and temperature on the batch growth of Candida lipolytica on gas oil are investigated. Growth parameters are presented for two sets of experiments. The shape of growth curves was basically similar to the system composed of n-hexadecane dissolved in dewaxed gas oil, in spite of the complex nature of the substance. All of the batch growth curves exhibited a linear growth region. The rate of linear growth and its length varied with change in dispersed phase volume. The effect of temperature on growth rate was investigated for temperatures ranging from 23°C to 34°C. The results show a smaller activation energy during linear growth than during the early stages of batch growth. These results are analyzed from the viewpoint of growth models presented previously. The results indicate that growth at drop surfaces is important and that segregation effects may be important.
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  • 60
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    Biotechnology and Bioengineering 14 (1972), S. 637-645 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The enzyme invertase has been covalently coupled to porous glass particles. The product is extremely stable over a long period of time. Kinetic values for the immobilized enzyme are similar to the native enzyme. Excellent enzymatic activity for the immobilized enzyme was exhibited over a broad pH range. The immobilized enzyme when continuously operated for one month was found to have an operational half-life of over 40 days.
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  • 61
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    Biotechnology and Bioengineering 14 (1972), S. 679-681 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 62
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inhibitory substrate levels are common in industrial fermentations and in biological waste-water treatment of many industrial wastes. Continuous microbial cultures are unstable to certain disturbances, such as shock loading by inhibitory substrates. Two feedback proportional control strategies are analyzed and compared for a simple model culture assumed represent able by the culture concentrations of biomass and a single rate-limiting and growth-limiting nutrient (substrate). One control strategy, the well known turbidostat, consists of adjusting culture holding time (e.g., by flow rate adjustment) in response to deviations in turbidity or some other measure of culture biomass concentration. The other control strategy is to adjust holding time in response to deviations in limiting nutrient concentrations in the culture. This second control strategy, termed the nutristat, can be superior to the turbidostat in many applications. The sign and magnitude of the dimensionless group {(X/YD)[dμ/dS]s}, is shown to be an important determinant, in the behavior of the open loop and the two closed loop processes. This characteristic group is positive when the specific growth rate is increased by increases in the nutrient concentration, zero when the growth rate is unaffected by the nutrient concentration, and negative in the presence of nutrient or substrate inhibition.The effects of process modifications and of modeling assumptions on the control of the process are discussed and more sophisticated control schemes are also proposed.
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  • 63
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    Biotechnology and Bioengineering 14 (1972), S. 1007-1026 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The quantitative changes in mitochondria and cytochromes during transition of Saccharomyces cerevisiae from one steady state to another, while growing in continuous culture under controlled environmental conditions, were followed.No Mitochondria, or mitochondria like structures, were detectable in electron micrographs of permanganate-fixed anaerobic cells. Microaerobiosis (3μM dissolved oxygen) was sufficient to visualize mitochondrial profiles and induce cytochromes and their sections had a reduced number of mitochondrial profiles compared with cells grown in limiting glucose.In the presence of ergosterol and Tween 80 mitochondriogenesis, whether induced by aerobiosis or glucose limitation, involved enhanced definition of crystal and outer mitochondrial membranes and increased number of profiles. Where membrane formation was limited, by the absence of aerobiosis involved eytochrome induction and profile visualization, but limited profile Proliferation; the adapted cells consequently contained fewer, but more eytochrome-enriched, mitochondria than cells adapted in the presence of ergosterol and Tween 80.Increase in dissolved oxygen from 3μM to 52μM further enhanced membrane definition and increased the size, but not the number, of mitochondrial profiles.Evidence, obtained by measurement of eytochrome concentration per unit mitochondrial volume and per unit crystal area, support the concept that mitochondriogensis and cytochrome synthesis are not synchronized process and that cytochromes are added to or depleted from the mitochondrial cristae in response to culture conditions.
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  • 64
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    Biotechnology and Bioengineering 14 (1972), S. 13-22 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A discrete optimally sensitive controller is developed which yields steady-state feedback control of a three-stage biochemical reactor system in spite of system parameter variations. A feedback law is implemented that estimates those variations which cause the output states to deviate from nominal, and adjusts the control policy in light of these variations.
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  • 65
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    Biotechnology and Bioengineering 14 (1972), S. 61-73 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic model has been presented to explain the growth of microorganism on solid hydrocarbons. The model is based on the assumption that metabolite produced by the growing cells helps the dissolution of the solid substrate in the aqueous medium. The linear behavior of the growth curve predicted by the model is verified experimentally.
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  • 66
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    Biotechnology and Bioengineering 14 (1972) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 67
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    Biotechnology and Bioengineering 14 (1972), S. 173-177 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method for large reduction of nucleic acid content of Saccharomyces cercvisae is described. This method is based on yeast suspension in phosphate solution (50mM), heat shock following the Maul et al. (Nature 228, 181 (1970)) procedure, and dialysis or washing with phosphate solution of alkaline pH. When the extraction process is carried out at pH 12, sodium phosphate can be replaced by sodium chloride with the same results. Under these conditions the protein mg/nucleic acid mg ratio attains values of 50-60, (10 times the initial ratio). At this alkaline pH, washing can be done with distilled water with equally good results.
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  • 68
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    Biotechnology and Bioengineering 14 (1972), S. 629-635 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A “stick test” for the detection of lactose has been developed based upon the enzyme lactase chemically bound via Procion brilliant orange to DEAE-cellulose. Utilization of the bound rather than the free enzyme allows an ease in its addition to and removal from the reaction medium as well as a facile control of reagent quality and quantity. The bound enzyme “stick” may be reused for several determinations.
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  • 69
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Conditions for the preparation of microcapsules containing asparaginase by interfacial polymerization were investigated.The activity of microcapsules prepared under the optimal conditions was about 37% compared with that of native asparaginase. Particle size of microcapsules could be controlled by determining the stirring rate and concentration of Span 85. The membranes of microcapsules were resistant to mechanical shock or attack of chymotrypsin, and no leakage of asparaginase from microcapsules was observed.
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    Biotechnology and Bioengineering 14 (1972), S. 799-810 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growing cultures, washed cells, and cell-free preparations of Gluconobacter melanogecnus IFO 3293 converted L-sorbose to 2-keto-L-gulonic acid, to D-sorbitol (which was metabolized further) and to 5-keto-D-fructose.
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  • 71
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    Biotechnology and Bioengineering 14 (1972), S. 725-736 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Release of protein from a suspension of bakers' yeast (Saccharomyces cerevisiae) by disruption in an industrial agitator mill has been studied. Protein release on disruption in the mill is a first-order rate process. The rate constant is dependent on at least six parameters. Increased disruption efficiency was obtained at higher agitator speeds, greater loading of bead attritive elements and lower rates of upward recycle of yeast suspension through the mill. An increase in temperature from 5 to 42°C was accompanied by a reduction in disruption efficiency of approximately 20%. With optimal values of the parameters examined the throughput of the mill is 5.32 kg/hr of soluble protein for 90% disruption.
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  • 72
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    Biotechnology and Bioengineering 14 (1972), S. 737-752 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of a nonionic surfactant, polyoxyethylenesorbitan monolaurate (Tween 20), on the hen egg-white lysozyme catalyzed lysis of a dried cell suspension of Micrococcus lysodeikticus is analysed. A rate enhancement of up to 70% is observed in the presence of surfactant at concentrations above the critical micelle concentration. This activity increase may be explained by postulating the existence of a micelle-enzyme complex in which enzyme molecules are bound to micelles with preferential orientation of their active sites.The reaction is found to be second order with respect to substrate. A mechanism is postulated in which a substrate particle is assumed to be an energy-furnishing collision partner to the enzyme-substrate complex. This mechanism correlated data over a wide range of enzyme and substrate concentrations.Data from kinetic, ultrafiltration, ultraviolet, and fluorescence studies provide convincing evidence for the existence of a micelle-lysozyme complex. The results suggest that it is possible that immobilized enzymes mat in general be more reactive than corresponding free enzymes.
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  • 73
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    Biotechnology and Bioengineering 14 (1972), S. 831-841 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Resting cell suspensions of Sepedonium ampullosporum have been used successfully in the pilot plant, transformation of 9β 10α-pregna-4, 6-dien-3, 20-dione to its 16α-hydroxy derivative. The resting cell enzyme system acted as a stable respiratory unit up to 150 hr after resuspension in water. Semicontinuous addition of substrate to the same cell suspension reduced overall conversion lime by 67%.Aeration and agitation were important factors affecting conversion rates. The hydroxylating system had a critical oxygen concentration above 90% saturation of air in water. Hydroxylase activity was inhibited by cyanide an d totally inhibited by the respiratory inhibitor antimycin A at concentrations much less that that concentration required to block normal respiration.
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  • 74
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    Biotechnology and Bioengineering 14 (1972) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 75
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    Biotechnology and Bioengineering 14 (1972), S. 915-938 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The integro-differential growth model of Eakman, Fredriekson, and Tsuehiya has been employed to fit cell size distribution data for Schizosaccharomyces pombe grown in a chemostat under severe product inhibition by ethanol. The distributions were obtained with a Coulter aperture and an electronic system patterned after that of Harvey and Marr. Four parameters - mean cell division size, cell division size standard deviation, daughter cell size standard deviation, and a growth rate coefficient - were calculated for models where the cell growth rate was inversely proportional to size, constant, and proportional to size. A fourth model, one where sigmoidal growth behavior was simulated by two linear growth segments, was also investigated. Linear and sigmoidal models fit the distribution data best. While the mean cell division size remained relatively constant at all growth rates, standard deviation of division size distribution increased with increasing holding times. Standard deviation of the daughter size distribution remained small at all dilution rates. Unlike previous findings with other organisms, the average cell size of Schizosaccharomyces pobme increased at low growth rates.
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  • 76
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    Biotechnology and Bioengineering 14 (1972), S. 985-1006 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The chemolithotroph, Hydrogenomonas eutropha, was tested for its ability to utilize a variety of single nitrogen sources during growth in an atmosphere of H2—O2—CO2 The present data show that H. eutropha can utilize the nitrogen from many, but not all, amino acids, several sulfur-containing amino acids, glucosamine, and two aliphatic amides. The nitrogen concentration that supported maximum growth for NH4Cl, L-glutamate, L-glutamine, urea, and glycine was in the 0.010-0.019M range. H. eutropha failed to remove the nitrogen from primary and secondary amines, eycloleucine, tert-DL-leucine, DL-p-fluorophenylalanine, DL-5-methyltryptophan, creatine, and creatine. This microorganism was able to partially degrade at least six substituted indoles and/or tryptophan catabolites and six substituted imidazoles and/or histidine catabolites. All of a series of 17 dipeptides were able to serve as a nitrogen source for growth in the absence of NH4Cl. Extracts of H. eutropha were able to catalyze the hydrolysis of 16 α-dipeptides, 2 tripetides, a tetrapeptide, a polypeptide, a β-aspartyl peptide, 2 γ-glutamyl peptides, a N-acetyl amino acid, and 4 amino acid amides. These results emphasize the effectiveness of H. eutropha in utilizing a wide diversity of organic nitrogenous compounds containing amino and amide groups, heterocyclic rings, and peptide bonds.
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  • 77
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    Biotechnology and Bioengineering 14 (1972), S. 1039-1044 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 78
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Single-stage continuous fermentations to produce xanthan gum have been run at dilution rates (D) from 0.023 to 0.196 hr-1. Xanthan production rate (XPR) was a function of D. XPR increased from 0.34 g/hr/kg at D = 0.023 hr-1 to the maximum 0.84 g/hr/kg at D = ca. 0.15 hr-1. At D 〉 0.15 hr-1 XPR decreased and at the highest D studied (0.196 hr-1) was 0.69 g/hr/kg. Yield of xanthan from glucose consumed was 81-89%. Steady states ended between 6.5 and 8.7 turnovers when a variant strain occurred.
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  • 79
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    Biotechnology and Bioengineering 14 (1972), S. 75-92 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The bacterium Acetobacter suboyxdans and the yeast Saccharomyces carlsbergensis have been grown together on a synthetic medium in a chemostat. Mannitol, the only carbon source fed to the fermenter, is oxidized by the bacteria to fructose. The yeast, which cannot attack mannitol, breaks down the fructose nearly completely. Eight steady states and five transitory periods after changes in flow rate have been analyzed to study the kinetics of the mixed culture. Separate cell concentrations were determined by a modified Coulter counter apparatus. Both sugars were monitored. Both bacteria and yeast may be modeled using Monod's equation, the latter with some deviations. The yeast is unable to grow beyond the washout point of the bacteria, even though its maximum growth rate is much higher. The yield of both organisms decreases with increasing dilution rate, as does their average cell size. After step changes in dilution rate, repeated oscillations of both sugar and cell concentrations usually occur before steady-state conditions are reattained. They are generally in phase, with no definite sign of a lag. Oscillations of yeast and fructose concentrations are more pronounced. Periods average about 6 hr and are not correlated with fermentation conditions or equipment variables. Repeated oscillations are not found after step-downs in pure cultures of A. suboxydans, leading to the conclusion that the instability in mixed cultures may be caused by a feedback mechanism from the yeast to the bacteria.
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  • 80
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pseudomonas fluorescens (ATCC 11150) was grown in batch and continuous culture in minimal media with sodium maleate as growth-limiting sole organic carbon source. Growth was followed by turbidity and dry weight measurements. Gross composition of washed cells (relative amounts of protein, lipid, RNA, and DNA) and the distribution of amino acids in protein hydrolyses of the cells were determined for cells grown in continuous culture at various dilution rates. Extracellular concentrations of the original carbon source and a number of metabolites were monitored by a total carbon analysis, ion exchange chromatography, and ultraviolet-visible scans of cell-free supernatants and chromatographic fractions, thereof.Substrate inhibition by maleate was a major factor in the growth kinetics of both batch and continuous cultures. Excessive maleate concentration caused instability in continuous cultures. By appropriate operation, much higher specific growth rates (0.305/hr) could ultimately be achieved in continuous culture compared to batch culture (0.174/hr). Adaptation was responsible for only part of the differences between batch and continuous cultures; the differing distribution of metabolites were also major factors.
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  • 81
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetic behavior of heterogeneous microbial populations of sewage origin was studied in a single-stage isothermal continuous flow completely mixed aeration tank. A series of experiments were carried out at various dilution rates using glucose as the growth limiting substrate. The steady-state behavior of the system was observed at each dilution rate and the results were found to fit fairly well with the steady-state equation bayed on the Monod model with an endogenous respiration term included, i.e., μ = μmS/(Ks + S) - Kd. The growth kinetics of cells harvested at steady state for each dilution rate were studied using batch experiments. The multiple response data of the system as functions of time were used to estimate the parameter values in the above kinetic model. It was found that values of the growth parameters changed significantly and systematically with cell population. For example, values of μm were high at high dilution rates and low at low dilution rates. It was also found that only those batch growth parameters from cells obtained at fairly high dilution rates are comparable with those estimated by the results of steady-state operations. The results of this investigation suggest that (1) different cell populations pre dominated at different steady-state dilution rates, with high dilution rates resulting in predominantly fast-growing organisms and low dilution rates resulting in predominantly slow-growing cells, and (2) risk exists in any randomly picked batch experiment to predict the steady-state behavior of the system when heterogeneous microbial populations must be used.
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  • 82
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    Biotechnology and Bioengineering 14 (1972), S. 207-231 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetic behavior of heterogeneous microbial populations of sewage origin was studied in a single-stage, isothermal, continuous flow, completely mixed aeration tank. A series of experiments were carried out at various dilutions rates using glucose as the limiting substrate. The cell dry weight and substrate concentration in terms of chemical oxygen demand (COD) were continuously monitored. The results indicate that reproducible steady-state conditions can generally be obtained; however, multiple steady states were observed at dilution rates near washout. At low dilution rates (below about 0.1 hr-1) the contribution of microorganism decay became appreciable. Using the multiresponse data of cell dry weight and COD, the parameter values in various existing growth models were estimated. The analyses of variance and residuals revealed that models proposed by Moser, Monod, and Contois, each with a decay term added, were significantly better than the other models which were tested.
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  • 83
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fermentation kinetics of the homofermentative organism Lactobacillus delbrueckii in a glucose-yeast extract medium is studied in both batch and continuous culture under conditions of controlled pH. From a graphical analysis of the batch data, a mathematical model of the process is derived which relates bacterial growth, glucose utilization, and lactic acid formation. The parameters in the model represent the activity of the organism and are a function of pH, having a maximum value at about 5.90. In a continuous stirred tank fermentor (CSTF), the effect of pH, feed concentration, and residence time is observed. The feed medium is a constant ratio of two parts glucose to one part yeast extract plus added mineral salts. An approximate prediction of the steady-state behavior of the CSTF can be made using a method based on the kinetic model derived for the batch case. In making step changes from one steady state to another, the transient response is observed. Using the kinetic model to simulate the transient period, the calculated behavior qualitatively predicts the observed response.
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  • 84
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    Biotechnology and Bioengineering 14 (1972), S. 253-265 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: If inhibitory substrates are being utilized in a well-stirred biological reactor, microbiological growth on the walls of the reactor can create a scale-up problem. A simple model is proposed which shows that without such growth, of the three existing steady states only one is stable and nontrivial, but with wall growth the trivial, stable, steady state (washout) is impossible. In addition, wall growth reduces the region over which three steady states are feasible and reduces the minimum residence time for which there is only one steady state that corresponds to a high conversion. Thus, a laboratory process with a high surface area to volume ratio can give an over optimistic prediction of both necessary residence; time and stability of the full scale process unless wall growth is accounted for.
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  • 85
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    Biotechnology and Bioengineering 14 (1972), S. 267-271 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 86
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    Biotechnology and Bioengineering 14 (1972), S. 273-277 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 87
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    Biotechnology and Bioengineering 14 (1972), S. 279-280 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 88
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 89
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    Biotechnology and Bioengineering 14 (1972), S. 285-289 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 90
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    Biotechnology and Bioengineering 14 (1972), S. 517-532 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A unique method is described by which large yields of secondary metabolites arc produced on solid substrates. The process involves the use of moist substrates which are continuously agitated in appropriate fermentation equipment. The amount of agitation, aeration, and moisture can be varied. Extremely high yields of secondary metabolites such as ochratoxin and aflatoxin were obtained using Aspergillus and Penicillium species. The process prevents sporulation of the fungus and because of the nature of the solid substrate makes recovery of the product easier than in conventional liquid media. The substrates include rice, corn, wheat, and other cereals.
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  • 91
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of the following factors on the measurement of yeast concentration in liquid hydrocarbon fermentations was studied: surfactant, type (Tween 20, Tween 80, and G 3300), yeast concentration (0.215 to 0.272 and 3.37 to 4.08 g/liter, as dry matter), oil concentration (8.32 and 61.6 g/liter), surfactant, concentration (0.515, 1.030, 1.545, and 2.060 g/liter), and time of contact of the surfactant with the oil-yeast-aqueous medium mixture (2 and 10 min). The statistical significance of the obtained results was determined.
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  • 92
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    Biotechnology and Bioengineering 14 (1972), S. 675-678 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 93
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    Biotechnology and Bioengineering 14 (1972) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 94
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    Biotechnology and Bioengineering 14 (1972), S. 851-855 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 95
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    Biotechnology and Bioengineering 14 (1972), S. 885-914 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Tubes with immobilized enzymes on the inner wall, called open tubular heterogeneous enzyme reactors, were prepared by binding enzymes either directly to the tube inside surface or to a layer of a porous matrix attached to the inner wall. Kinetic studies of the hydrolysis of N-benzoyl-L-arginine ethylester as a model reaction indicated that the reaction was kinetically controlled in reactors with surface bound trypsin and the kinetic parameters were evaluated by conventional methods. On the other hand, substrate diffusion in both the porous matrix and the bulk substrate solution strongly affected the rate of reaction in porous layer trypsin reactors. The highest overall rates of reaction were obtained when the reaction was bulk diffusion controlled and the measured rates were in agreement with those calculated from expressions derived from heat transfer theory. The design of reactors for the limiting cases of kinetic and bulk diffusion controlled reaction as well as a method for the determination of substrate diffusivity are outlined.
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  • 96
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    Biotechnology and Bioengineering 14 (1972), S. 1027-1030 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 97
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    Biotechnology and Bioengineering 14 (1972), S. 1035-1038 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Tab.
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  • 98
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    Biotechnology and Bioengineering 14 (1972), S. 1045-1046 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 99
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    Biotechnology and Bioengineering 14 (1972), S. 93-101 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In experiments with one freshwater (Chlorella pyrenoidosa) and three marine organisms (Phaeodactylum tricornutum, Cyclotella nana, and Chaetoceros galvestonensis), mecury was more toxic than the other metals tested (silver, cadmium, lead, and copper); and its toxicity is comparatively irreversible. Growth was monitored by changes in fluorescence of the cultures over a 3-day test period. The toxicity of the mercury varied inversely with the concentrations of nutrients present. Preliminary experiments indicate that mercury in the form of mercuric chloride is more than as dimethylmercury.
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  • 100
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    Biotechnology and Bioengineering 14 (1972), S. 151-171 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the present study optimal policies have been evaluated for the production of gramicidin S in multistage continuous culture. An economic objective function was developed which took account of the number and size of the reaction vessels, the costs involved in antibiotic extraction, substrate costs, and variability in the selling price of gramicidin S. Optimal values of temperature and pH were 28.3 and 7.24, respectively, and independent of the stage in the system. Using the discrete maximum principle it was shown that a “cut-off” point existed for the selling price of the antibiotic below which production was no longer profitable. Furthermore it was established that beyond 3 stages in a multistage system, only marginal gains in profitability could be made (viz., an increase in 6.3% on going from a 3-stage to a 4-stage system).
    Additional Material: 3 Ill.
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